In fact, in this type of boat the crew which constitutes the ballast of the boat must constantly place itself in a good position to effectively assure the balance. To compensate for the heel, it must put itself as counter-balance by being, for example, at the gunwale in case of a monokeel boat construction. When the wind is very strong, this counter-balance must be increased by leaning outwardly while passing the feet through slings to stop the outward dipping of the boat; this corresponds to the action called return movement. Finally, in racing sailboats a crewman must put himself completely outside the cockpit with the help of a system known as a "trapeze".